Effectiveness and Safety of Vitamin D₃ Supplementation in Adults: Insights from an Indian Retrospective Analysis

Objective: To evaluate the efficacy and safety of vitamin D₃ supplementation in vitamin D-deficient Indian adults. Design: Retrospective, multi-center, observational study. Methods: Medical records of 8,685 patients were reviewed for demographics, comorbidities, baseline and post-supplementation serum vitamin D levels, perceived health improvement, and adverse events. Descriptive statistics and correlation analyses were performed. Results: Mean age was 53.7 years (SD = 12.3); common comorbidities included diabetes (14.6%) and hypertension (7.9%). Serum vitamin D increased significantly from 18.57 to 32.86 ng/mL (p < 0.001). All patients received 60,000 IU weekly for up to 12 weeks, followed by 1,000 IU daily maintenance. Significant improvements were seen only with ≥8 weeks of supplementation. Post-therapy, 32.1% reported excellent and 35.8% very good overall health. No adverse events occurred in 98.1%; mild, transient effects were reported in 1.6%. Conclusion: Vitamin D₃ supplementation significantly improved serum vitamin D levels with meaningful benefits observed only after at least 8 weeks of therapy, with a favourable short-term safety profile, supporting its use in managing vitamin D deficiency in Indian adults.